U.S. patent application number 14/798793 was filed with the patent office on 2016-01-21 for static mixer.
The applicant listed for this patent is Eberspacher Exhaust Technology GmbH & Co. KG. Invention is credited to Silvia CALVO, Andreas RESCH.
Application Number | 20160017785 14/798793 |
Document ID | / |
Family ID | 53442606 |
Filed Date | 2016-01-21 |
United States Patent
Application |
20160017785 |
Kind Code |
A1 |
RESCH; Andreas ; et
al. |
January 21, 2016 |
STATIC MIXER
Abstract
A static mixer (12) for an exhaust system (7) for mixing a
reducing agents with an exhaust gas flow (8). The static mixer (12)
has a plurality of guide blades (14) for deflecting the exhaust gas
flow (8). A reduced flow resistance is obtained when at least one
of the guide blades (14) has a perforation (25) through which the
exhaust gas flow (8) can flow.
Inventors: |
RESCH; Andreas; (Boblingen,
DE) ; CALVO; Silvia; (Esslingen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eberspacher Exhaust Technology GmbH & Co. KG |
Neunkirchen |
|
DE |
|
|
Family ID: |
53442606 |
Appl. No.: |
14/798793 |
Filed: |
July 14, 2015 |
Current U.S.
Class: |
60/324 ;
366/336 |
Current CPC
Class: |
B01F 3/022 20130101;
B01F 5/0602 20130101; B01F 2005/0639 20130101; F01N 3/2892
20130101; F01N 2240/20 20130101; F01N 3/103 20130101; B01F
2005/0625 20130101; B01F 5/0616 20130101; F01N 3/2066 20130101;
B01F 5/0451 20130101 |
International
Class: |
F01N 3/28 20060101
F01N003/28; B01F 5/06 20060101 B01F005/06; F01N 3/20 20060101
F01N003/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 2014 |
DE |
10 2014 213 746.2 |
Claims
1. A static mixer for an exhaust system for mixing a reducing agent
with an exhaust gas flow, the static mixer comprising: a plurality
of guide blades for deflecting the exhaust gas flow, wherein at
least one of the guide blades comprises a perforation through which
the exhaust gas flows.
2. A static mixer in accordance with claim 1, wherein the
perforation comprises a plurality of passage openings, which
passage openings are arranged within a lateral outer contour of the
respective at least one of the guide blades.
3. A static mixer in accordance with claim 2, wherein the passage
openings comprise an oblong cross section and are arranged parallel
to each other and next to each other along a blade length, measured
from a blade footing to a blade tip, of the respective at least one
of the guide blades.
4. A static mixer in accordance with claim 1, wherein the
perforation comprises at least one passage opening, which is open
on a side at a leading edge or at a discharge edge of the
respective at least one of the guide blades.
5. A static mixer in accordance with claim 1, wherein the
perforation comprises a plurality of passage openings, which are
open on a side at a leading edge or at a discharge edge of the
respective at least one of the guide blades, whereby the passage
openings open on the side are oblong and are sloped towards a blade
length of the respective at least one of the guide blades as well
as towards a blade width of the respective at least one of the
guide blades.
6. A static mixer in accordance with claim 1, wherein the
perforation is formed from a single passage opening.
7. A static mixer in accordance with claim 6, wherein the passage
opening is arranged within a lateral outer contour of the
respective at least one of the guide blades.
8. A static mixer in accordance with claim 1, wherein the
respective at least one of the guide blades has a single- or
multi-curved course along a blade length thereof.
9. A static mixer in accordance with claim 1, wherein the
perforation comprises at least one passage opening with an opening
edge, which is detached along an entire circulation thereof.
10. A static mixer in accordance with claim 1, wherein the
perforation comprises at least one passage opening with an opening
edge, which opening edge is connected along at least one
circulation section with a tilting device, which at least partly
covers the associated passage opening and/or is arranged sloped
and/or offset towards an area of the guide blade adjacent
thereto.
11. A static mixer in accordance with claim 10, wherein the
respective tilting device is a free-cut and tilted area of the
respective at least one of the guide blades for producing the
respective passage openings with a displacement of the area to a
tilted position.
12. A static mixer in accordance with claim 10, wherein the at
least one such tilting device has a central area and two lateral
areas, whereby the central area extends essentially parallel to the
respective at least one of the guide blades and is connected with
the respective at least one of the guide blades via the two lateral
areas.
13. A static mixer in accordance with claim 10, wherein the at
least one tilting device is designed as a wing, which wing is
connected with the respective at least one of the guide blades only
on one side and is arranged otherwise detached in relation to the
respective at least one of the guide blades.
14. A static mixer in accordance with claim 10, wherein: the
respective at least one of the guide blades has a step in a
longitudinal direction of the blade; and the at least one tilting
device is formed by a step, which step is spaced apart from the
step formed in the respective at least one of the guide blades.
15. An exhaust system for an internal combustion engine, the
exhaust system comprising: an injector for introducing a liquid
reducing agent into an exhaust gas flow; and at least one static
mixer arranged downstream of the injector with regard to the
exhaust gas flow, the at least one static mixer comprising: a
plurality of guide blades for deflecting the exhaust gas flow,
wherein at least one of the guide blades comprises a perforation
through which the exhaust gas flows.
16. An exhaust system in accordance with claim 15, wherein the
perforation comprises a plurality of passage openings, which
passage openings are arranged within a lateral outer contour of the
respective at least one of the guide blades.
17. An exhaust system in accordance with claim 15, wherein the
perforation comprises at least one passage opening, which is open
on a side at a leading edge or at a discharge edge of the
respective at least one of the guide blades.
18. An exhaust system in accordance with claim 15, wherein the
perforation comprises a plurality of passage openings, which are
open on a side at a leading edge or at a discharge edge of the
respective at least one of the guide blades, whereby the passage
openings open on the side are oblong and are sloped towards a blade
length of the respective at least one of the guide blades as well
as towards a blade width of the respective at least one of the
guide blades.
19. An exhaust system in accordance with claim 15, wherein the
perforation is formed from a single passage opening arranged within
a lateral outer contour of the respective at least one of the guide
blades.
20. An exhaust system in accordance with claim 15, wherein the
perforation comprises at least one passage opening with an opening
edge, which opening edge is connected along at least one
circulation section with a tilting device, which at least partly
covers the associated passage opening and/or is arranged sloped
and/or offset towards an area of the guide blade adjacent thereto.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority under 35
U.S.C. .sctn.119 of German Patent DE 10 2014 213 746.2 filed Jul.
15, 2014, the entire contents of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention pertains to a static mixer for an
exhaust system for mixing a reducing agent with an exhaust gas
flow. The present invention also pertains to an exhaust system
equipped with such a mixer.
BACKGROUND OF THE INVENTION
[0003] In exhaust systems of internal combustion engines there is
in certain applications the need to introduce a reducing agent into
the exhaust gas flow. For example, a fuel can be introduced into
the exhaust gas flow upstream of an oxidation catalytic converter
in order to increase the heat of the exhaust gas flow due to a
reaction of the fuel in the oxidation catalytic converter, for
example, in order to heat up a particle filter that is arranged
downstream to its regeneration temperature. It is likewise common
in SCR systems to introduce an aqueous urea solution upstream of an
SCR catalytic converter into the exhaust gas flow, whereby SCR
denotes Selective Catalytic Reaction. The aqueous urea solution can
be converted by means of thermolysis and hydrolysis into ammonia
and carbon dioxide, which makes a conversion of nitrogen oxides
into nitrogen and water possible in the SCR catalytic
converter.
[0004] In order to optimize the respective reaction, which shall be
brought about with the reducing agent introduced, it is of high
importance to mix the introduced reducing agent with the exhaust
gas flow as homogeneously as possible. Frequently, the reducing
agent is introduced in liquid form into the exhaust gas flow, such
that it is also necessary to evaporate the reducing agent as
completely as possible. A static mixer mentioned in the
introduction, which brings about an intense mixing of exhaust gas
and reducing agent, is used for this purpose.
[0005] A static mixer, which has a plurality of guide blades for
deflecting the exhaust gas flow, is known from EP 1 985 356 A2. For
this purpose, the guide blades project into the exhaust gas flow
and are set towards the exhaust gas flow in order to be able to
bring about the respective deflection of the exhaust gas flow. As a
result of this, the guide blades at the same time form impact areas
for the reducing agent introduced in liquid form. Due to the impact
of the guide blades with the exhaust gas flow, these guide blades
have a relatively high temperature, such that the guide blades at
the same time are used as evaporation surfaces for reducing agent
deposited thereon.
[0006] An as large as possible impact surface, on the one hand, and
an as intensive as possible deflection of the flow, on the other
hand, result each in an increased flow resistance of the mixer. The
flow resistance of the mixer brings about a rise in pressure in the
exhaust system upstream of the mixer, which reduces the efficiency
of an internal combustion engine equipped with the exhaust system
or increases its fuel consumption.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to provide an improved
embodiment for a static mixer of the type mentioned above or for an
exhaust system equipped therewith, which is characterized
especially by a comparatively low flow resistance, while at the
same time a sufficient mixing and especially a sufficient
evaporation can be achieved.
[0008] According to the invention, a static mixer is provided
comprising a plurality of guide blades for deflecting the exhaust
gas flow. At least one of the guide blades comprises a perforation
through which the exhaust gas flows.
[0009] According to another aspect of the invention, an exhaust
system is provided for an internal combustion engine. The exhaust
system comprises an injector for introducing a liquid reducing
agent into an exhaust gas flow and at least one static mixer
arranged downstream of the injector with regard to the exhaust gas
flow. The static mixer comprises a plurality of guide blades for
deflecting the exhaust gas flow. At least one of the guide blades
comprises a perforation through which the exhaust gas flows.
[0010] The present invention is based on the general idea of
equipping at least one of the guide blades, and preferably all
guide blades, each with a perforation, through which the exhaust
gas, i.e., a part of the exhaust gas flow, can flow. It has been
shown that such a perforation can significantly reduce the flow
resistance of the mixer, whereby at the same time turbulence is
sufficiently generated by the perforation to bring about the
desired intensive mixing.
[0011] In the present context, a perforation is defined as any
interruption of a structure of the guide blade that is otherwise
closed or impermeable to exhaust gas. Thus, openings, through
holes, tiltings and the like are perforations.
[0012] The perforation of the respective guide blade may in this
case have a plurality of passage openings which are each arranged
within a lateral outer contour of the respective guide blade
according to a preferred embodiment. Thus, the respective guide
blade has an outer contour which is not compromised by the passage
openings. In this way, the flow-guiding function of the respective
guide blades is only comparatively slightly compromised by the
perforation.
[0013] According to an advantageous variant, the passage openings
may have a round or an angular cross section. Likewise, the passage
openings may have a punctiform or else an oblong cross section.
Passage openings with oblong cross section may be linear or
single-curved or multi-curved.
[0014] In another advantageous variant, the passage openings may
each have an oblong cross section and be arranged parallel to each
other and next to each other along a blade length measured from a
blade footing to a blade tip of the respective guide blade. In such
an embodiment, a low flow resistance can be shown for the
respective guide blade with sufficient or improved mixing
effect.
[0015] According to a variant, the passage openings may be arranged
with their oblong cross sections sloped toward the blade length and
sloped toward a blade width measured from a leading edge to a
discharge edge of the respective guide blade. By means of this
measure, the mixing effect can, in addition, be affected and
optimized.
[0016] According to another embodiment, the perforation may have at
least one or a plurality of passage openings, which are open on the
side at a discharge edge or at a leading edge of the respective
guide blade. In this embodiment, these passage openings open on the
side have an effect on a lateral outer contour of the respective
guide blade. For example, targeted flow separations and swirl may
be generated thereby, which may have advantageous effects on an
intensive mixing. All the passage openings of the perforation are
preferably open on the side at the discharge edge or at the leading
edge. However, an embodiment, in which the perforation has at least
one open passage opening on the outer contour of the guide blade
and at least one passage opening lying completely within the outer
contour, is also generally conceivable.
[0017] In a variant which assumes that a plurality of passage
openings open on the side are provided, the passage openings open
on the side may be oblong and be sloped towards a blade length of
the guide blade as well as towards a blade width of the guide
blade. As before, the blade length extends from a blade footing up
to a blade tip, while the blade width extends from the leading edge
to the discharge edge.
[0018] In another variant, the passage openings open on the side of
the leading edge may be sloped with regard to the blade length
opposed to the passage openings of the discharge edge. As a result
of this, the flow-conducting action of the guide blades can be
optimized with regard to an improved mixing.
[0019] In an alternative embodiment the perforation in at least one
of the guide blades may be formed from a single passage opening.
Such a singular passage opening is advantageously dimensioned
larger in terms of its flow cross section than the individual
passage openings of the perforations explained above, which are
formed by a plurality of passage openings. Accordingly, such a
perforation has a reduced flow resistance.
[0020] This singular passage opening may be arranged within a
lateral outer contour of the respective guide blade in one variant.
In other words, an embodiment, in which the passage opening does
not have an effect on the outer contour of the guide blade, is
preferred here as well. It can essentially extend from a blade
footing up to a blade tip as well. Further, the passage opening may
have a pointed design, whereby the tip of the passage opening can
then be arranged in the area of the blade tip. As an alternative,
the passage opening may also be provided with a constant width.
[0021] Basically, it is likewise possible to develop the singular
passage opening open on the side on a blade tip of the respective
guide blade. If this singular passage opening open on one side is,
in addition, designed as oblong, quasi a division of the guide
blade in the area of the passage opening can thus be achieved. Such
a passage opening, open in the area of the blade tip, may lead to
an especially low flow resistance in the area of the respective
guide blade.
[0022] In another advantageous embodiment the respective guide
blade may have a single- or multi-curved course along its blade
length. While the guide blades usually have a linear design, it is
suggested here now to equip the respective guide blade with a
curved course with regard to its central longitudinal axis. The
central longitudinal axis of the respective guide blade extends
thereby from the blade footing to the blade tip approximately in
the center with regard to the blade width. A single-curved guide
blade then has a sickle-shaped design. A twice-curved guide blade
then has an S-shaped design. In addition or as an alternative, the
respective guide blade may have a twisting with regard to its
central longitudinal axis, which leads to a varying pitch angle
along the blade length.
[0023] In another advantageous embodiment, the mixer may have a
cylindrical pipe body, which encloses a flow cross section through
which the exhaust gas flow can flow in the circumferential
direction and from which the guide blades project inwards. In this
type of construction, the guide blades may be especially arranged
detached radially inwards in the area of their blade tips.
Furthermore, the guide blades may be arranged in a contactless
manner relative to each other.
[0024] Especially advantageous is a variant, in which the pipe body
with all guide blades is produced from a single sheet metal body by
means of shaping. As a result of this, the mixer can be produced at
a comparatively low cost by means of punching and shaping
processes.
[0025] In another advantageous embodiment, the perforation may have
at least one passage opening with an opening edge, which is
detached along its entire circulation. Such a detached opening edge
may be produced by a punching process in an especially simple
manner in case of a guide blade designed as a sheet metal body.
Preferably, the circulation is completely closed, when the
respective passage opening is arranged within the outer contour of
the guide blade. If, on the other hand, the passage opening is
designed open on the side on the outer contour of the guide blade,
the circulation of the opening edge on the outer contour is
interrupted.
[0026] Advantageously, all passage openings of the respective guide
blade are equipped with such a detached opening edge.
[0027] In another embodiment, the perforation may have at least one
passage opening with an opening edge, which is connected with a
tilting device (angled feature) along a circulation section. The
tilting device may at least partly cover the associated passage
opening. In addition or as an alternative, the tilting device may
be sloped towards an area of the guide blade adjacent thereto. In
addition or as an alternative, the tilting device may be arranged
at least partly offset towards an area of the guide blade adjacent
thereto. The arrangement of the tilting device is thereby
preferred, such that the tilting device at least partly covers the
passage opening and accordingly brings about a flow deflection of
an exhaust gas flow passing through the passage opening. Such a
tilting device at the opening edge of the passage opening improves
the mixing action of the guide blade. At the same time, the flow
resistance can be reduced by the flow deflection with the tilting
device.
[0028] The tilting device is advantageously formed integrally in
one piece with the respective guide blade. The respective tilting
device can especially advantageously be an area of the respective
guide blade that is free-cut and tilted for producing the
respective passage opening. Thus, the respective guide blade can be
equipped in an especially simple manner with the passage openings
and tilting devices adjacent thereto.
[0029] According to an advantageous variant, provisions may be made
for at least one such tilting device to have a central area and two
lateral areas, whereby the central area extends essentially
parallel to the respective guide blade and is connected with the
respective guide blade via the two lateral areas. As a result of
this, an especially efficient covering of the respective passage
opening is obtained.
[0030] Further, according to another variant, provisions may be
made for at least one such tilting device to be designed as a wing,
which is connected only on one side with the respective guide blade
and is otherwise arranged detached to the respective guide blade.
Such a wing acts as a flow-guiding element, such that the flow of
the respective passage opening can be especially favorably affected
by means of such a wing.
[0031] In addition, provisions may advantageously be made for at
least one such tilting device to be formed by a step, which is
spaced apart in a blade longitudinal direction from a (different)
step formed in the respective guide blade. The respective step may
be produced by means of bending the guide blade twice, preferably
by approx. 90.degree., transversely to its longitudinal
direction.
[0032] It is clear that the different variants mentioned above for
the perforation--insofar as useful--can be achieved at at least one
single guide blade or in case of various guide blades of the same
mixer, i.e., especially passage openings of different sizes and/or
geometries and/or with or without tilting devices.
[0033] The mixer presented here is heated exclusively by the
exhaust gas flow during the operation of the exhaust system, such
that it operates free from external energy with regard to its
evaporation action.
[0034] In an exhaust system according to the present invention,
which is suitable for discharging combustion waste gases in an
internal combustion engine, an injector is provided for introducing
a liquid reducing agent into the exhaust gas flow, whereby, in
addition, at least one mixer of the type described above is
arranged downstream of this injector with regard to the exhaust gas
flow. The exhaust system may, furthermore, have an SCR catalytic
converter downstream of the mixer or an oxidation catalytic
converter downstream of the mixer.
[0035] Further important features and advantages of the present
invention appear from the subclaims, from the drawings and from the
associated description of the figures based on the drawings.
[0036] It is apparent that the features mentioned above and those
still to be explained below can be used not only in the respective
given combination, but also in other combinations or alone, without
going beyond the scope of the present invention.
[0037] Preferred exemplary embodiments of the present invention are
shown in the drawings and are explained in detail in the following
description, whereby identical reference numbers refer to identical
or similar or functionally identical components. The various
features of novelty which characterize the invention are pointed
out with particularity in the claims annexed to and forming a part
of this disclosure. For a better understanding of the invention,
its operating advantages and specific objects attained by its uses,
reference is made to the accompanying drawings and descriptive
matter in which preferred embodiments of the invention are
illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 is a circuit-diagram-like schematic diagram of an
internal combustion engine with an exhaust system, which contains a
static mixer;
[0039] FIG. 2 is an isometric view of the mixer;
[0040] FIG. 3 is an axial view of the mixer;
[0041] FIG. 4 is a layout of the mixer;
[0042] FIG. 5 is a simplified view of a guide blade of the mixer in
one of various embodiments;
[0043] FIG. 6 is a simplified view of a guide blade of the mixer in
another of various embodiments;
[0044] FIG. 7 is a simplified view of a guide blade of the mixer in
another of various embodiments;
[0045] FIG. 8 is a simplified view of a guide blade of the mixer in
another of various embodiments;
[0046] FIG. 9 is a simplified view of a guide blade of the mixer in
another of various embodiments;
[0047] FIG. 10 is a simplified view of a guide blade of the mixer
in another of various embodiments;
[0048] FIG. 11 is a simplified view of a guide blade of the mixer
in another of various embodiments;
[0049] FIG. 12 is a simplified view of a guide blade of the mixer
in another of various embodiments;
[0050] FIG. 13 is a simplified view of a guide blade of the mixer
in another of various embodiments;
[0051] FIG. 14 is a simplified view of a guide blade of the mixer
in one of various embodiments and partly with associated sectional
view or variant A;
[0052] FIG. 15 is a simplified view of a guide blade of the mixer
in another of various embodiments and partly with associated
sectional views or variants A, B and C;
[0053] FIG. 16 is a simplified view of a guide blade of the mixer
in another of various embodiments;
[0054] FIG. 17A is a simplified view of another embodiment of a
guide blade of the mixer;
[0055] FIG. 17B is a simplified view of another embodiment of a
guide blade of the mixer;
[0056] FIG. 17C is a simplified view of another embodiment of a
guide blade of the mixer;
[0057] FIG. 17D is a simplified view of another embodiment of a
guide blade of the mixer;
[0058] FIG. 18 is a simplified view of a guide blade of the mixer
in another of various embodiments;
[0059] FIG. 19 is a simplified view of a guide blade of the mixer
in another of various embodiments and partly with associated
sectional views or variants A and B; and
[0060] FIG. 20 is an isometric view of a guide blade of the mixer
from FIG. 19 in the area of a perforation.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0061] Referring to the drawings, according to FIG. 1, an internal
combustion engine 1 comprises an engine block 2 which contains a
combustion chamber 4 each in a plurality of cylinders 3. Pistons,
which are not shown here, are arranged with adjustable stroke in
the cylinders 3, such that the internal combustion engine 1 is a
piston engine. A fresh air feed unit 5 is provided for supplying
the combustion chambers 4 with fresh air. A corresponding fresh air
flow 6 is indicated by an arrow. In order to be able to discharge
combustion gases from the combustion chambers 4, the internal
combustion engine is, in addition, equipped with an exhaust system
7. An exhaust gas flow 8 is indicated by an arrow. In the example
of FIG. 1, the exhaust system 7 is equipped with an SCR system 9,
which has an injector for introducing a liquid reducing agent into
the exhaust gas flow 8, an SCR catalytic converter 11 for reducing
nitrogen oxides with the aid of the previously injected reducing
agent as well as a static mixer 12. With regard to the flow
direction of the exhaust gas flow 8, the SCR catalytic converter 11
is arranged downstream of the injector 10. Further, the mixer 12,
with regard to the direction of flow of the exhaust gas flow 8, is
arranged downstream of the injector 10 and upstream of the SCR
catalytic converter 11. The exhaust system 7 has an exhaust line
13, into which the above-mentioned components of the SCR system 9
are integrated.
[0062] According to FIGS. 2 and 3, the mixer 2 has a plurality of
guide blades 14 which are each used for deflecting the exhaust gas
flow 8. In the preferred example shown the mixer 12 has, moreover,
a cylindrical pipe body 15, which encloses a flow cross section 16,
through which the exhaust gas flow 8 can flow, in the
circumferential direction 17. The circumferential direction 17 is
in reference to a central longitudinal axis 18 of the pipe body 15
or of the mixer 12. The guide blades 14 project from the pipe body
15 inwards, i.e., in the direction of the central longitudinal axis
18. Thereby, the direction of extension of the respective guide
blade 14 has at least one radial component. Further, this direction
of extension may optionally also have an axial component.
[0063] Advantageously, this pipe body is produced integrally with
the guide blades 14 from a single sheet metal body 19, namely by
means of shaping, such that the mixer 12 is ultimately a single
shaped sheet metal part. A layout of the sheet metal body 19 or of
the mixer 12 is shown in FIG. 4. The sheet metal body 19 has a
jacket section 20, which forms the pipe body 15 in the shaped
state. The guide blades 14 project from this jacket section 20. In
the layout of FIG. 4, the individual guide blades 14 are already
free-cut, whereby individual sections are designated with 21. The
sections 21 pass over at the jacket section 20 into round holes 22
to avoid a tear formation at this passing over.
[0064] In order to produce the mixer 12 from the planar sheet metal
body 19 in FIG. 4, the blades 14 are each bent over a bending edge
23 and the jacket section 20 is bent over the central longitudinal
axis 18 of the mixer 12 in the circumferential direction 17.
Thereby, the longitudinal ends 24 of the jacket section 20 may form
a butt joint at the pipe body 15 in the circumferential direction
17 and be fastened to each other.
[0065] As can be inferred from FIGS. 2 through 4, the guide blades
14 in the example shown of the mixer 12 are exclusively designed on
a leading side of the pipe body 15. For orientation, the exhaust
gas flow 8 is indicated by a flow arrow. Likewise, an embodiment is
conceivable, in which all guide blades 14 are arranged on a
discharge side of the pipe body 15. Further, it is conceivable to
provide such guide blades 14 at the pipe body 15 both on the
leading side and on the discharge side each. The use of two mixers
12, which are arranged one behind the other in the direction of
flow of the exhaust gas flow 8, is also conceivable.
[0066] As can be inferred from FIGS. 2 through 4, at least one of
the guide blades 14 is equipped with a perforation 25. The
perforation 25 is thereby configured, such that the perforation 25
traverses the otherwise closed guide blade 14, such that the
exhaust gas flow 8 or partial flows of the exhaust gas flow 8 can
flow through the guide blade 14 through the respective perforation
25. Even though not all guide blades 14 are equipped with such a
perforation 25 in the examples of FIGS. 2 through 4, an embodiment
is, however, preferred, in which all of the guide blades 14 have
such a perforation 25. Even though various perforations 25 are
provided in the individual guide blades 14 in FIGS. 2 through 4, an
embodiment is preferred, in which the perforated blades 14 have an
identical perforation 25 each.
[0067] Various embodiments of such a perforation 25 are explained
in detail below based on FIGS. 5 through 20. For example, the
respective perforation 25 may have a plurality of passage openings
26, which are arranged within a lateral outer contour 27 of the
respective guide blade 14. FIGS. 5 through 10, 15 and 18 show
embodiments, in which all passage openings 26 of the perforation 25
are arranged within the outer contour 27 of the guide blade 14. In
the embodiment shown in FIG. 5, all passage openings 26 are
equipped with a round and punctiform cross section. In particular,
the passage openings 26 show each a round cross section.
[0068] In the embodiment shown in FIG. 6, the passage openings 26
are designed as oblong and linear. Further, they extend parallel to
each other. Furthermore, the parallel arranged passage openings 26
are arranged next to each other along a blade length 28. The blade
length 28 is thereby measured from a blade footing 29 up to a blade
tip 30. In a mixer according to the embodiment shown in FIGS. 2
through 4, the blade footing is arranged at the pipe body 15, while
the blade tip 30 is arranged detached in the area of the central
longitudinal axis 18.
[0069] The embodiment shown in FIG. 7 corresponds to the embodiment
shown in FIG. 6, providing that the passage openings 26 have
different cross sections. On the other hand, FIG. 8 shows an
embodiment, in which the oblong passage openings 26 have an
angular, in this case parallelogram-like cross section. Further,
the passage openings 26 are arranged sloped with regard to their
oblong cross section towards the blade length 28 as well as towards
a blade width 31. The blade width 31 is thereby measured from a
leading edge 32 up to a discharge edge 33 of the respective guide
blade 14. By contrast, the oblong passage openings 26 in the
examples of FIGS. 6 and 7 are aligned parallel to the blade width
31.
[0070] FIG. 9 now shows an embodiment, in which a plurality of
oblong passage openings 26 are arranged one behind the other in the
direction of the blade width 31, which passage openings 26 are
arranged in this case, in addition, offset to each other in the
direction of the blade length 28. Further, the passage openings 26
are arranged next to each other along the blade length 28, as well
as aligned parallel to each other and parallel to the blade width
31. In the perforation 25 shown in FIG. 9, the passage openings 26
have markedly smaller cross sections through which flow is possible
than in the embodiments of FIGS. 5 through 8.
[0071] FIG. 10 shows an embodiment, in which the passage openings
26 have an oblong cross section and thereby are single-curved.
Regardless of the geometry and number of the passage openings 26,
FIG. 10 shows, in addition, an embodiment, in which the respective
guide blade 14 has a twice-curved course along its blade length 28.
As a result of this, the guide blade 14 has an S-shaped course with
regard to its blade length 28.
[0072] In the embodiments shown in FIGS. 11 and 16, the respective
perforation 15 has a plurality of passage openings 26, which are
open on the side on the leading edge 32 or on the discharge edge 33
of the respective guide blade 14. As a result of this, the passage
openings 26 have an effect on the lateral outer contour 27 of the
guide blade 1. In the example of FIG. 14, all passage openings 26
of the perforation 25 are designed as open on the side. Further,
all passage openings 26 are oblong in this case and provided with a
rectangular cross section. In addition, the passage openings 26
arranged on the leading edge 32 are each arranged parallel to each
other and next to each other with regard to the blade length 28.
The passage openings 26 provided on the discharge edge 33 are also
arranged parallel to each other and next to each other in the blade
length 28. Furthermore, the passage openings 26 shown are aligned
sloped both towards the blade length 28, i.e., towards the blade
width 31. In addition, provisions are thereby made, in addition,
for the passage openings 26 of the leading edge 32 to be sloped
with regard to the blade length 28 opposed to the passage openings
26 of the discharge edge 33. In particular, the passage openings 26
are arranged in a mirror-symmetrical manner with regard to a
central longitudinal axis of the respective guide blade 14, as a
result of which the perforation 25 shows a sweepback and the guide
blade 14 has a fishbone-like shape. The sweepback of the
perforation 25 is aligned toward the blade tip 30 for this.
[0073] On the other hand, only a single passage opening 26 open on
the side is provided on the leading edge 32 and on the discharge
edge 33 each in FIG. 16.
[0074] While the examples of FIGS. 5 through 11, 15, 17 and 18 each
show perforations 25, which have a plurality of passage openings
26, FIGS. 12 through 14 and 19, 20 show an embodiment each, in
which the perforation 25 has only a single passage opening 26 each.
At least in the examples of FIGS. 12 through 14, this passage
opening 26 is provided with an oblong cross section, which is
aligned parallel to the blade length 28. Furthermore, the
respective passage opening 26 extends over an essential
longitudinal section of the respective guide blade 14. In these
examples, the respective passage opening 26 extends over at least
75% of the blade length 28. In the example of FIG. 12, the passage
opening 26 has a rectangular cross section, while a triangular
cross section is provided in the embodiment shown in FIG. 13. A
rectangular cross section is provided again in FIG. 14. In FIGS. 12
and 14, the passage opening 26 has a constant cross section along
the blade length 28, while in FIG. 13 the cross section decreases
in the direction toward the blade tip 30. In the examples of FIGS.
12 through 14 and 19, 20, the passage opening 26 remains within the
lateral outer contour 27 of the associated guide blade 14. In
another embodiment, the passage opening 26 may, on the other hand,
be so arranged and/or so dimensioned that it is open on the side at
the blade tip 30, as a result of which the guide blade 14 is quasi
divided in the area of this passage opening 26.
[0075] In the embodiments of FIGS. 5 through 13, the passage
openings 26 are each equipped with an opening edge 34, which is
detached along is entire circumferential extent (circulation). In
the embodiments of FIGS. 5 through 10, 12 and 13, in which the
passage openings 26 are arranged within the outer contour 27, the
respective circulation of the opening edge 24 is closed, while the
circulation in the embodiment shown in FIG. 11, in which the
passage openings 26 are open on the side at the outer contour 27,
is interrupted in each case by the opening on the side of the
respective passage openings 26.
[0076] In the embodiments of FIGS. 14 through 20, the perforation
25 may have at least one passage opening 26, whose opening edge 34
is connected with a tilting device 35 along a circulation section.
In the embodiments of FIGS. 16 through 18, this tilting device 35
is arranged sloped towards an area of the respective guide blade 14
adjacent thereto. Thereby, the respective tilting device 35 brings
about a covering of at least one part of the respective passage
opening 26. In FIGS. 16 through 18 in the rectangular passage
opening 26, three consecutive, linear circulation sections each
form a free opening edge 34, while the remaining fourth, linear
circulation section is then connected with the tilting device 35,
as a result of which the respective tilting device 35 forms a wing
36. The tilting device 35 advantageously forms a free-cut and
tilted area of the guide blade 14 in the creation of the respective
passage opening 26. Thus, the respective tilting device 35 is
formed integrally in one piece with the guide blade 14.
[0077] In FIGS. 14 through 20, provisions are made for the
perforation 25 to have at least one passage opening 26 with an
opening edge 34, which is connected with a tilting device 35 along
at least one circulation section, which tilting device 35 at least
partly covers the associated passage opening 26 and/or is arranged
sloped and/or offset towards an area of the guide blade 14 adjacent
thereto.
[0078] In FIGS. 14 and 15, provisions are made for at least one
such tilting device 35 to have a central area 36 and two lateral
areas 37, whereby the central area 36 extends essentially parallel
to the respective guide blade 14 and is connected via the two
lateral areas 37 with the respective guide blade 14.
[0079] On the other hand, in FIGS. 17 and 18, provisions are made
for at least one such tilting device 35 to be designed as a wing
36, which is characterized in that it is connected only on one side
with the respective guide blade 14, while it is otherwise arranged
detached to the respective guide blade 14. These wings 36 may
thereby be integrated into the outer contour 27 as in FIG. 16, such
that their passage openings 26 are open on the side. Likewise, a
distance to the outer contour 27 may be maintained in another
embodiment. Two different geometries for the wings 36 are shown in
FIG. 16. FIG. 17 shows other variants A, B, C and D for the
geometric shape of such wings 36. Thus, FIG. 17A shows a wing 36
with a linear profile. FIG. 17B shows a wing 36 with a concave bent
profile in the tilting direction. FIG. 17C shows a wing 36 with a
convex bent profile in the tilting direction. FIG. 17D shows, on
the other hand, a wing 36 with an aerodynamically shaped profile,
especially a drop profile.
[0080] FIG. 18 shows, in an exemplary manner, an embodiment, in
which the formation of the perforation 25 by means of a plurality
of various passage openings 26 with tilting devices 35 (left half
in FIG. 18) and without tilting devices 35 (right half in FIG. 18),
which differ from each other, moreover, by different geometries and
cross sections.
[0081] FIGS. 19 and 20 show another embodiment for a special
perforation 25, in which the guide blade 14 is equipped with a step
38, which is formed by means of two bending edges 39. In the area
of the perforation 25 are provided two other bending edges 40,
which are arranged offset to the above-mentioned bending edges 39
in a blade longitudinal direction 42, which runs parallel to the
blade length 28 and in which the guide blade 14 is bent in the
opposite direction. Accordingly, the tilting device also forms a
step 41, which is arranged offset in the blade longitudinal
direction 42 to the step 38 of the guide blade 14. As a result of
this, two open cross sections, spaced apart from one another, which
make possible a lateral inflow and lateral outflow of the exhaust
gas, are formed in a blade transverse direction 43, which extends
parallel to the blade width 31.
[0082] Even though in the preferred embodiment shown here the mixer
is designed as a shaped sheet metal part, it may also be designed
as a cast part or a sintered part in another embodiment. The
respective perforation 25 is then advantageously worked in
later.
[0083] While specific embodiments of the invention have been shown
and described in detail to illustrate the application of the
principles of the invention, it will be understood that the
invention may be embodied otherwise without departing from such
principles.
* * * * *